The present application relates to an ignition coil and method of manufacturing.
In recent years, efforts in the automotive industry have been directed to developing ignition coils that are located at each of the spark plugs of an internal combustion engine. Each spark plug therefore has its own ignition coil. A direct connection to the spark plug is preferred because it eliminates the need for high voltage wires from a distributor to each of the spark plugs. Instead, all of the wiring to the spark plugs from the power train control unit (PTCU) of the engine can be provided using inexpensive and compact low-voltage wiring.
Past efforts to provide a direct connection, however, have been complicated because of the limited amount of space at the top of a spark plug in modern engines. The spark plug typically is received in a rather narrow bore hole. Each ignition coil therefore must either fit within the narrow bore hole, or project out therefrom. The option of having the ignition coil project out from the bore hole is typically impractical because it prevents the space above the bore hole from being occupied by other engine components or the vehicle""s hood.
As a result, the efforts to provide an ignition coil at each spark plug has resulted in the development of xe2x80x9cpencil coilsxe2x80x9d. Pencil coils have an outer diameter that is small enough for the pencil coil to fit within the typical spark plug""s bore hole. Even when insertion into a bore hole is not necessary, a reduction in size is desirable because it saves space under the vehicle""s hood.
When charging of the coil is initiated, a transient voltage is created. This kind of sparking event is commonly referred to as a spark-on-make event or condition because historically it would occur when the breaker points of the ignition system made contact to commence charging of the ignition coil. The term xe2x80x9cspark-on-makexe2x80x9d, as used in this disclosure however, is not limited to situations where conventional breaker points are used. To the contrary, it refers to any situation where initiation of coil or ignition system charging causes a spark at one or more of the spark plugs. Traditionally, this kind of sparking event is considered undesirable because it was not timed for proper engine operation. In order to control or prevent the make voltage from breaking down the spark gap a diode is employed. As referred to herein xe2x80x9cmakexe2x80x9d voltage defines the voltage induced across the secondary coil when the primary coil is initially energized.
In addition, electromagnetic noise created by the spark event is capable of being received by the high-voltage end of the ignition coil. This electromagnetic noise is undesirable and a suppressor is utilized to reduce the electromagnetic interference of the spark noise.
To be most effective these components (suppressor and diode) should be placed as close as possible to the high-voltage output of the coil. Real estate, however, in a system where both of these devices are needed typically dictates that the suppressor is positioned at the high-voltage side of the coil and a diode is positioned at the low voltage side. This requires two components, both of which are somewhat specialist.
A suppressor diode for use in an ignition coil, the suppressor diode provides a resistive inductor for preventing xe2x80x9cmake voltagesxe2x80x9d from breaking down a spark gap of a spark plug. In addition, the resistive inductor prevents electromagnetic interference from the spark plug. The suppressor diode is configured for securement in a confined area of an ignition coil. In particular, the suppressor diode is located between a high-voltage terminal and a high-voltage end of a secondary coil.
The suppressor diode includes a spool with a winding surface, a diode is molded into the spool and the diode has a first end connection and a second end connection. The diode is oriented to prevent current flow from the first end connection to the second end connection. A suppressive winding is disposed onto the winding surface; an end cap electrically connects the first end connection of the diode to the suppressor winding. A first termination electrically connects the suppressor winding to a high-voltage end of a secondary winding and a second termination electrically connects the second end of the diode to a high-voltage terminal of the ignition coil.
An ignition coil for an internal combustion engine, the ignition coil comprises a primary winding and a secondary winding. The primary winding is adapted to be electrically connected to a low-voltage ignition signal. The secondary winding is inductively coupled to the primary winding with more turns than the primary winding so that the secondary winding develops a high-voltage ignition signal in response to switching of the low-voltage ignition signal. A suppressor diode is located between the high-voltage end of the secondary winding and a high-voltage terminal of the ignition coil. The suppressor diode prevents electromagnetic interference from the spark plug as well as unwanted xe2x80x9cmake voltagesxe2x80x9d from appearing at the spark gap.
Still other objects, advantages, and features of the present invention will become more readily apparent when reference is made to the accompanying drawings and the associated description contained herein.